Journal of the American Geriatric Society May 30, 2020 [epub]

Ryan McGrath, PhD, Peggy M. Cawthon, PhD, Matteo Cesari, MD, PhD, Soham Al Snih, MD, PhD, Brian C. Clark, PhD: From North Dakota State University, University of California, San Francisco, University of Milan, University of Texas, and Ohio University. This study cites 47 references.

As the population ages, understanding the intricate connections between physical health and cognitive function becomes paramount. A recent study, encompassing a national sample of aging Americans, delves into the associations between handgrip strength (HGS) asymmetry, weakness, and lower cognitive functioning. Here, we dissect the key findings that illuminate the intricate interplay between muscular strength and cognitive well-being.

The Study: Bridging Muscles and Minds

The study, involving 17,163 subjects aged 50 years or older, aimed to unravel the potential links between handgrip strength and cognitive function. Utilizing a handgrip dynamometer, researchers measured HGS, considering factors such as hand dominance and weakness. Cognitive function was assessed through a validated screening tool, examining various cognitive domains.

Key Points from the Study:

  • Significance of HGS:
  • Low muscle strength, often assessed by HGS, is acknowledged as a reliable measure of overall muscle function.
  • Weakness has broad associations with various health conditions, including cognitive impairment and Alzheimer’s disease.
  • Neural Systems and Motor Skills:
  • The study supports the “common-cause hypothesis,” suggesting a shared foundation between HGS and cognitive function.
  • The neural systems governing coordinated movement, assessed through HGS, may offer insights into overall nervous system function and brain health.
  • HGS as an Indicator of Intrinsic Capacity:
  • HGS is viewed as a convenient assessment of strength capacity, representing a subdomain within the framework of intrinsic capacity.
  • Intrinsic capacity encompasses all physical and mental attributes an individual can draw upon as they age.
  • Predictive Power of Asymmetry and Weakness:
  • Combining HGS asymmetry and weakness enhances the predictive capacity for health problems, including cognitive impairment.
  • Each group with weakness and HGS asymmetry demonstrated greater odds of lower cognitive functioning.
  • Accelerated Declines in Cognitive Functioning:
  • The coexistence of HGS asymmetry and weakness may predict accelerated declines in cognitive functioning.
  • The study highlights the importance of examining both factors to better forecast cognitive declines.
  • Hand Dominance and Brain Hemisphere Activation:
  • Hand dominance, often reflecting brain hemisphere dominance, may offer insights into cognitive declines.
  • Motor asymmetries, including HGS asymmetry, may be linked to deficient brain hemisphere activation.
  • Feasibility of HGS Measurement:
  • HGS is deemed feasible to measure and provides robust health information.
  • The study emphasizes the valuable health insights that can be derived from a simple and practical assessment.
  • Implications for Understanding Motor and Neural Functioning:
  • The findings deepen our understanding of how motor and neural functioning intertwine with strength capacity and cognitive function.
  • Examining weakness and HGS asymmetry provides a more comprehensive prediction of lower cognitive functioning than assessing weakness alone.
  • Hand Laterality as a Indicator:
  • Hand dominance may serve as an indicator of cognitive declines associated with shifts in brain hemisphere functioning.
  • Neural circuits established for motor function may also play a role in cognitive function.
  • Potentiating Cognitive Declines:
  • The presence of weakness and HGS asymmetry may potentiate declines in cognitive functioning, emphasizing the interconnectedness of physical and cognitive health.

In conclusion, the study sheds light on the intricate relationship between handgrip strength and cognitive function in aging Americans. As we uncover the multifaceted connections between muscles and minds, these findings pave the way for a more holistic approach to health, encompassing both physical strength and cognitive vitality in the aging population.